Apparatus for impregnating webs



Oct. 2, 1945.

| E. HAHN APPARATUS FOR IMPREGNATING A WEB Filed July 12, 1940 INVENTOR Zia/W120 HAHN BY M a roll.

Patented Oct. 2, 1945 APPARATUS FOR BKPREGNATIN G WEBB Leonard E. Hahn, Kansas City, Mo., assignor to .Oertain-Teed Products Corporation, New York,

N. Y., a corporation of Maryland M Application July 12,1940, Serial No. 345,093

volume.

This invention relates to an apparatus for impregnating a web of felted fibrous material with an impregnating or saturating material. The invention especially relates to control in the impregnating and saturating process of the conditions under which the impregnation takes place. The invention particularly relates to the impregnating or saturating with asphalt of felts for the manufacture of roofing materials.

The impregnating of a web of felted fibers has been carried out in the prior art in various ways. The invention is concerned with a modification of the prior-art processes of saturating such a web and particularly the invention constitutes an improvement in the process described in the patent to John E. Miller, No. 1,636,750, July 26, 1927.

In the process of the Miller Patent 1,636,750 asphalt saturant of a low melting point is applied to the web at one face thereof in successive applications and so as to drive air and moisture out of the web at the other face thereof as the asphalt so applied passes through the web .to the other face thereof. In the process as disclosed in the Miller patent, when the web has been thus treated to a, sufflcient degree it is passed through a bath or dip tank of asphalt to complete the saturation of the web at said other face. Thereafter, the web travels in one or more loops to permit the saturant to set before winding the web into It is an object of the invention to secure a greater degree of saturation of the felted web and more uniform saturation than has heretofore been possible with the prior art methods and apparatus.

It is also an object of the invention to secure these results while maintaining the'advantages of the usual processes and apparatus, particularly that of the Miller patent.

It is a further object of the invention so to apply the asphalt saturant, particularly in the final stages of such application, as to enable the felted web to carry as great, an amount-of the asphalt. saturant as is possible when the sealing coatings which are carried upon the faces of the web in the ordinary roofing products are applied.

It is a feature of the invention that the absorption of the saturant by the felted web is carried out and controlled under such conditions in the final stages of the impregnation of the felted web that the web carries substantially all of the saturant that it is possible for it to' carry at its temperature and at the temperaur e of the saturant thus carried, when, that is to say, substantially immediately before, the sealing coatings are applied to the faces of the web.

It is a furtherfeature of the invention that said absorption of the saturant in said final stages of the impregnation is so carried out and controlled that substantially the web is prevented from absorbing air or moisture until said sealing coatings cover and seal the faces of the web.

As in the practice of the process of the Miller patent so in the preferred process of the invention, asphalt saturant or impregnating material heated to the temperature necessary to secure the requisite fluidity and viscosity for saturation is applied at one face of the web at successive points therealong as it travels through the saturating apparatus, driving out air and moistureat the opposite face, until the web has absorbed sufilcient asphalt for the asphalt to appear upon and to blacken a substantial part of the area of the other face of the web. In some cases this application of saturant at the first face of the web may be carried to a point where the opposite face becomes fully blackened or even carrying an excess of the saturant at said opposite face. Baturant may be applied to the opposite face to further saturate the web and to secure an excess at said opposite face orthe web may be passed through a bath of asphalt to secure excess upon both faces of said web.

. In any case, it is an important feature of the invention that upon both faces of the web is carried an excess of asphalt greatly in excess of that which the web at its temperature and at the temperature of the asphalt saturant carried thereon will absorbduring said final stages of saturation to supply the asphalt necessary to keep the felted structure of the web substantially completely filled up with asphalt while the web and the layers of asphalt thereon cool.

This excess of asphalt on the faces of the web 1 also is substantially more than that which will just be absorbed by and substantially completely fill up the felted structure of the web when it and the asphalt thereon have cooled to the necessary extent to be ready to receive the sealing coatings of asphalt.

A purpose of insuring, as does the invention, that the web shall carry upon its faces this superabundant amount of asphalt, ,that is, an amount of asphalt over and above that which will have been absorbed .by the web to substantially Just completely fill its felted structure at the time at which the sealing coatings are applied thereon without excess of said saturant upon the faces which would produce a wet sheet, is that the asphalt being drawn into the web from said layers shall be kept in proper condition of fluidity for being absorbed andthat it shall be immediately available at the surface'of thefelt for passage thereinto to the exclusion of air and moisture. To bring about these conditions for absorption of the asphalt by the web the amount of the excess on the faces of the sheet is controlled at a plurality of points along the travel of the web. At a point adjacent the point at which the last application of the asphalt saturant to the web is made the amount of asphalt in the layers is controlled, that is, limited, by removal of part of the initially present large excess. To secure absorption by the .web of the requisite amount of asphalt from said layers of excess upon these faces as the web cools in its travel from the saturating apparatus to the point at which the sealing coatings are applied thereto, a substantial travel of the web is provided to afford sufilcient time for the felted structure of the web to draw into itself saturant from said layers carried upon the faces of the web and-to maintain the full impregnation of the web at all stages of the cooling of the we prior to receiving said sealing coatings.

In order to insure that this absorption shall take place and that the web shall be in proper condition, that is,- filled up with the saturant but without excess to cause wetness when the sealing coatings are applied, the invention provides that limited, initially at the start of coolingand as the cooling of the web and its saturant proceeds.

' When this absorption and drawing in of the asphalt saturant, from the layers of excess on the web has proceeded to the proper degree, the.

superabundant excess remaining on the faces of necessary for the purposes, successive removals of portions of the layer of asphalt maybe effected'at a plurality of points along the travel of the web in the cooling zone. In any case, however, after such removal more asphalt still retained upon the faces of the web as it travels through the first part of the cooling zone than is required for the ultimately fully saturated and coated web. I p

The amount which remains upon the face of the web is then reduced at the point of. final removal of the excess, that is, upon entering the final part of the cooling zone, to be that which as the web arrives at the coating bath will just fully impregnate the web'without its being wet upon any substantial area of its faces. removal is effected before the saturant has congealed by reduction of its temperature to such an extent that removal cannot properly be accomplished and at such a'point that the excess remaining upon the sheet'shall not chill and ,congeal before reaching said point of application of the sealing coatings.

The invention accomplishes more effective con.

trol of the impregnating process and more complete saturation of the finished impregnated and coated web than heretofore has been secured.

' It accomplishes this result by carrying a' conthe web is removed to leave substantially an saturant at the temperature thereof and of the web when it enters the coating bath. Under these conditionsthe web will not .be wet upon any substantial area thereof at the time of application of the sealing coatings. It will, however, carry all the asphalt it can carry in its felted structure, to the exclusion of air and moisture so that only 'the sealing coatings thereafter immediately applied, as the,web further cools with concomitant contraction of the saturant and of the coatings, will be drawn into the felted structure. A sheet or a web carrying as much asphalt saturant as possible and completely sealed by the sealing coatings against moisture and air is thus obtained.

It is desirable that the amount of superabundant excess of asphalt maintained in the layers upon the faces of the web travelling through the cooling zone shall not be so great that the exterior portions of these layers of excess become congealed and thus retard the cooling of the web and the absorption of asphalt thereby from said layers. Moreover, too great an amount of asphalt in the layers of excess saturant limits the cooling because such layers carry. an amount of heat which tends to maintain the heat of the web, thus preventing its cooling and the absorption of asphalt thereby. The initial removal of a portion of the asphalt layer above referred to to secure a controlled and limited' amount of superabundantexcess asphalt in these layers in some cases alone may be sufficient ,for the proper conditions for cooling of the web and absorption of the asphalt thereby. If

trolled excess of the saturant upon the saturated web as it cools and finally limits the amount of this saturant so that this excess will be completely absorbed by and completely fill the web as the sealing coatings are applied thereto.

It is a further feature of the invention that the length of travel and therefore the length of time provided for absorption by the web while carrying this superabundant excess may be varied. The requisite condition during thistravel is that suflicient time shall be provided for absorption by the web of the necessary amount of saturant before final removal of thesuperabundant excess is effected. In view of the dif-. ferent absorptive. capacities of different webs, particularly in the manufacture of roofing materials, due to different weights per unit of area and different compositions of the 'felted web, differences in viscosity of the, saturant at the temperature at which it is applied, different operating speeds of the web in the machines, it is necessary to provide different times of travel beforeremoval of the superabundant excess is carried out. The invention, therefore, provides for variation of the length of travel of the web between the point of initial control and limitation of the superabundant excess and the point of final removal of the remainder of this excess which will reduce it to that which will just fill the web at the time at which the sealing coatings are applied.

Within the scope of the invention, however, in order to prevent chilling of the outer portions of the layer or layers of superabundant asphalt saturant carried by the web, I may provide means for heating the web during its travel. Moreover, if desired, 1 may also provide means for heating the web after the superabundant excess of asphalt has-been removed to reduce said excess to that which will be just absorbed by the web at the time of application of the sealing coatings.

It will be understood from the explanation above that the invention for the most part is concerned with supplementary or final stages of the process of impregnating and saturating the felted web. It comprises a preliminary or first treat--. ment such as that of the process of the Miller This final Patent No. 1,636,750 to secure complete irn..

pregnation of the webby the hot saturant. The.

' felted structure of the web throughout the cooling process but, at the time of its arrival at .the coating bath, without excess which produces wetness upon the face of the web constitutes an improvement over the prior art processes of impregnation.

The invention will be further understood from the description of the drawing to follow, in which the single figure shows diagrammatically an apparatus for saturating a web embodying the invention.

In the figure, at the left hand portion thereof, is illustrated diagrammatically an elevation of the saturator such as that disclosed in the Miller Patent No. 1,636,750. In this apparatus the sheet I is delivered over tension rolls 3 into a series of rolls 5 and 6, one placed above the other in order to form the loops or stretches of the felted web for carrying out the process of the Miller, Patent No. 1,636,750. For this purpose also are provided separate pipes l for directing a jet or spray of asphalt against one face of the web I as it passes over the rolls 5 and 6. In the particular embodiment illustrated in the figure, these sprays or jets are directed against that face of the web which is in contact with the lower rolls 5. This is the preferred arrangement because the excess of the asphalt so delivered to said sprays of theweb I may collect in the V shaped space formed between the circumference of the roll 5 and the web as it passes to said roll 5. Spreading of the asphalt over said face of the sheet is thus assisted.

According to the process of said Miller patent the rolls 6 are placed in sufiicient distance above the rolls 5 to provide a certain amount of travel of the web I after the application of the asphalt thereto at one face thereof. It is customary, however, before making-a second or subsequent application of the asphalt saturant by a succeedin spray I, to remove by scrapers 8 a portion of the previously applied asphalt which may have become congealed upon the outer portions of the layer of asphalt carried upon said face of the web. In this manner saturation of the web from one face thereof is carried out and continued until the saturant appears at the opposite face of the web. In many cases this operation may be carried to the extent .of causing the asphalt to blacken the major portion of said opposite face of. the web. In some cases the process may be continued until the whole of said opposite face is completely blackened. With a sufllcient number of sprays I, that is, sufficient number of applications of asphalt, and under proper conditions as to the absorptive capacity of the web, temperature, viscosity of the asphalt saturant, and other conditions, the saturation at said first face of the web may be carried to the point where an excess .of the saturant appears upon and (may be carried upon said opposite face of the web.

In the usual practice ,of the Miller process, after the asphalt has appeared upon a substantial part of the area of the opposite face, the web is passed through a bath of asphalt in a dip tank and asphalt largely in excess of that which can be the coating bath adheres'to the web. Some of the saturant thus carried by the faces of the web.

then is removed as by scraper to prevent the web being "we as it reaches the coating bath.

For the purposes of the invention, to secure application of the asphalt to the faces of the web greatly in excess of the requirements for the impregnation, the web may be similarly dipped in a bath 8 of saturating asphalt carried in a dip pan I0 by passing the web around a roll II immersed in said bath 9. Application, however,

' ofthe asphalt in such excess amount may be effected, if desired, by additional sprays at the The invention utilizes apparatus which has just been described to carry out the Miller process in the normal manner, but in saturating the web by means of the sprays or jets I, and by further application of asphalt as in the dip pan I0, an amount of asphalt greatly in excess of that necessary for final complete saturation of the coated web comes to be carried by the web. In order to secure the control of the amount of the asphalt ultimately carried by the coated web, the invention provides for the initial removal of a certain amount of said excess by means of the scrapers I3 and I4 placed at either side of the web as itcarries the layers of saturant thereon. The amount remaining on the web after passing scrapers I 3 and I4, however, is still in excess of that which ultimately will be carried by the coated web. This superabundant excess of asphalt is provided, and in controlled amount, in part in order that there will be available a certain amount of the asphalt which may be removed because it has become chilled as the sheet travels during the period of absorption of the asphalt and in part so that the amount remain,- ing upon the faces of the web will be such as not to interfere with 'or unduly reduce the coolin which is necessary during such travel for absorption of the asphalt. In some cases additional scrapers I5, I6, I1, and I8 may be provided, spaced along the travel of the web to reduce the excess asphalt in steps in order that the congealed portions may be removed at the proper time and the cooling assisted. As shown in the figure, the web I is passed over rolls 2n and 22 in loops to secure the necessary distance, that through the control rolls 30 which are set in such a relation to each other that a certain amount of asphalt carried on each face is removed therefrom. Control rolls 30 limit the amount of asphalt which may pass therebetween, carried by the web. The web, after leaving the rolls 30, therefore, carries upon its faces a definite amount of the saturating asphalt, and such an amount that in its further travel to the coating apparatus this asphalt substantially will be just absorbed by the felted structure. The excess removed from the web I by the rolls 30 may fall into the dip pan I I). It will be noted that the absorption section composed of rolls 20 and 22 also is arranged above the dip pan III so that any excess asphalt removed as by absorbed by the web as itcools 'on its way to V l scrapers I3, I4, I5, I6, 11 and I8 may fall into the bath 9 in said-dip pan I 0.

In order to obtain variation of the time available for absorption of the asphalt layer determined by scrapers I3, I4, I5, IS, IT and I8, with different .weights of felted webs, with different thicknesses,

and different absorptive capacities of these webs,

f with differences in the viscosities, capillary propis necessary for its absorption. The final control of the amount of asphalt effected by the rolls ill is carried out in consideration of a further time required for absorption by the web of the asphaltjust secure absorption of the excess asphalt which is upon the faces of the web as it leaves the rolls lacing of the sheet I for a shorter distance of travel than the lacing in full lines over the rolls 20, 22. The shorter distance of travel, affording a shorter time for absorption, would be used for a sheet of light weight, or one which is capable of absorbing the saturant rapidly, or with a saturant which was of such fluidity or other properties as to be readily absorbed. Moreover, particularly with webs of less weight which carry a less total amount of the saturant than webs of greater weight, a shorter time for absorption is necessary and a shorter distance of travel must be provided in order that undue cooling may be prevented and that there shall be retained upon the web the requisite excess for final control by the rolls 30.

With such a shortened travel of the web it will be necessary to adjust the scrapers, such as the scrapers I3 and I4, in order that no more than the requisite amount of superabundant excess asphalt shall be present upon reaching the control rolls 30. The amount of such superabundant excess and the actual length of travel over the rolls 22 and 24 would be determined also in part by the amount of chilling of the external portions of the asphalt layers which would occur in the travel between the scrapers I3 and I4 and the control rolls 30. If too great a travel for sucha light weight web occurs, excess chilling of the reduced amount of asphalt carried by the web may occur which would prevent not only proper control of the asphalt quantity from being effected by the rolls 30, but also penetration of the asphalt into theweb from this chilled layer. The web then would carry an undesirable layer of chilled asphalt upon reaching the coating apparatus.

Within the scope of theinvention, instead of additional rolls" 24 being provided in the apparatus, the rolls may be mounted to be adjustable between the positions 20 and the positions 24, so that any degree of length of travel, and therefore of time of travel between the scrapers I3 and I4 and the control rolls 30, may be secured.

It will be understood from the above description that the problem to which the invention is directed in part relates to the reduction of the temperature of the sheet and of the saturating asphalt carried thereby under such controls that the greatest degree Of saturation possible is obtained. In passing the web carrying upon its faces the layers of saturating asphalt through a set of rolls such as rolls 20, 22 and 24 to provide the requisite time for absorption, it is contemplated that there also shall be accomplished the requisite cooling of the sheet to secure absorption of the asphalt from said layers of asphalt and so as to follow the contraction of the asphalt already carried by the felted structure of the web. It will be understood that provision is made for control of both the amount of asphalt and the time which 30. In the usual roofing apparatus the web I maypass over a set of rolls 32 .and thence over roll 33 and in loops over a series of rolls 34 and 35. The web I also may hang in a loop between the roll 33 and the first roll 34.' From the last roll the sheet may pass to a set of pull rolls 3'! and thence in a loop in the usual manner-to a tension roll 42 above the coating pan 40. From the tension roll 42 the web passes into the bath of coating 43, around roll 44 immersed therein, and upward out of the bath 43 past a, set of scrapers 45 and 46 which limit the amount of the coating on the faces of the web. It then passes over supporting roll 41, thence under a spout 49 for further application of coating asphalt to the upper face of the web I. Thereafter the web I passes between control rolls 50 for determining the thickness of the coatings carried on the faces of the finished sheet. I

The distance between the control rolls 30 and the tension roll 42 for the most part is determined by the time necessary for absorption of that amount of excess asphalt saturant whichremains upon the faces of the web I upon leav- Dig the control rolls 30. As has been said above, this amount is that which substantially will be absorbed during the further reduction of the temperature of the web as it travels to the coating pan 40, and so that this absorption will be completed substantially just as the web reaches the coating pan. The passage of the web around rolls 32 and in the loops between rolls 33, 34 and 35 merely affords a practical method of securing the necessary distance In some cases a greater or less number of loops may be usedand under certain conditions the sheet may be passed directly fromthe roll'30 to the roll 42. The rolls 34 and 35 may be mounted so as to be adjustable to different positions, that is, closer or further apart;

as shown in dotted outline in the figure, in order to shorten or increase the length of travel of the web. It is an important feature of the invention, however, that the proper amount of time is provided for the particularweb being saturated with a given asphalt saturant for said excess of the saturant to be just absorbed in said travel before passing into the path 43 of the sealing coating in the coating pan 40.

In order to further control the absorption of the asphalt saturant carried upon the faces of the web, within the scope of my in'ventionI may control the temperature to which the web and the layers of asphalt saturant thereon are subjected. For example, to counteract chilling of the external portions of the layers of asphalt carried upon the web as referred to above, I may, if desired,

pass one or more loops of the web I as it travels .same inherent felted structure.

Heat loss from the external portions of. the asphalt layers upon the web may thus be restored or retarded so that the removal by the control rolls 30 of the superabundant excess may be properly accomplished and the web may be delivered from the rolls 30 with the proper amount of excess of the asphalt saturant for its absorption before reaching the tension roll 42 of the coating pan. The tempering chamber 60 may be constructed to include more than one loop. It also, if desired, may be located at one of the other loops through which the web 1 passes from the scrapers I3 and I4. The combination of the tempering chamber with the variation of the travel of the web between the scrapers l3 and I4 and the control rolls 30 may be utilized to more carefully control the condition of the asphalt saturant and the amount thereof ultimately carried by the saturated and coated web. The tempering chamber 60 may be so constructed and the temperature conditions therein so controlled as to determine the cooling of the web to the proper.

degree during its passage between the scrapers l3 and. the controllers 30. Moreover, a temperin chamber may be provided in connection with loops and rolls 34 and 35 which follow the control rolls 30 and precede the application of the sealing coating at coatingpan 40. Other means of heating and tempering maybe used and the m vention in its broad scope, is not limited to the use of the particular means illustrated in the figure.

As in the usual roofing machine the rolls :2 may be used for drying in the asphaltisaturant left upon the web by the control rolls 30. For

- this purpose the rolls maybe supplied with steam to heat the web or in some cases steam, at a lower temperature than the temperature of the web, or

other cooling fluid may abstract heat from the' web. This control of the temperature of the web and the provision of-the requisite distance, that is,.the requisite time of travel between rolls 30 and tension roll 42, both maybe utilized to secure the desired contraction and absorption of the excess asphalt so that when the coating is applied to the web at the coating-pan 40 the web will be fully saturated at the. temperature at which it enters the coating pan 43.

In the manufacture of roofing the speed of the web may be between 150 to 3'75 feet per minute. The time which is necessary for the excess saturantof the types ordinarily used in such manufacture to be absorbed by the web, that is, the time during which the web and the asphalt carried thereby cools to the condition for receiving the coating may varyfrom a few seconds to a minute or more. As has been indicated above, felts of greater weight will require more time than those of light weight even though they are of the and distance of travel of the web necessary for absorption of the asphalt between the initial removal of the portion of the excess by the scrapers l3 and I4 and the reduction of the superabundant excess to that required to complete the absorption, this reduction being -effected by the control rolls 30, is shown for typical roofing felts in the following table.

The corresponding approximate ranges of time and distance of web travel between control rolls 30 and mun necessary for the felted structure of tie web to absorb the reduced amount of excess asphalt remaining on the faces of the web after passing throught control calls 30 is shown for typical roofing felts in the following table.

Table II Weight of. g gl ielt lbs. Time in 28333 seconds 50 so to as 75 219 so 35 to 40 87 250 7a 40 to 45 281 In the above description by asphalt saturant as used in the manufacture of roofing is meant an asphalt having a melting point of between and ball and ring method. Such a .saturant in practice usually would be heated to a temperature of between 400 and 500 F. to secure the requisite fluidity for impregnation of the felted web.

By sealing coatings of asphalt in the above description is meant asphalts having a melting,

point of between 150 and 235 F. ball and ring method. Such an asphalt would be heated to a temperature of between 250 and 400 F. to secure the requisite flowability for application as a sealing coating upon the faces of the saturated felted web.

The web when saturated in the regular Miller process, that is, substantially as prepared prior to carrying out the supplementary treatment provided by the invention, would be substantially at the temperature of the saturant'carried there'- by, that" is, at a temperature of about 375 to 475 F. This temperature would be slightly lower than the saturant as it reaches the web from the sprays 'l of the figure. The temperature. of the asphalt saturant in the bath 9 may be approximately in the range between 350 and 450 'F. The temperature of the web may be reduced by passing through the cooling zone in its travel over the rolls 20 and 22 to a temperature in the range between 275 and 375 F. upon reaching the rolls 30, Similarly in the travel of the sheet between the rolls 30 and the roll 42 the temperature of the sheet may be further reduced to a temperature in the range between 200 F. and 300 F.

The above ranges of temperatures are given merely as an illustration. The invention is not limited to the particular range of temperatures expressed nor to particular-saturants or asphalts of the melting points given and the tempera.- tures at which they are applied.

The amount of the excess saturant over and above that carried by the web within its saturated felted structure upon leaving the dip pan III in saturating felted webs with asphalt saturants in the manufacture of roofing materials may amount .to between 200% and 400% of said amount of the saturant so carried within the felted structure. B means of the scrapers l3 and this excess'of saturant exteriorly carried by the web may be reduced to the desired 1 amount of superabundant excess and so as to be in the range of between 100% and 200% of the travel through a cooling zone to said means for amount of saturant which is within the impregnated felted web at said scrapers. As explained above, further removal of the-saturantmay beeil'ected by scrapers It, l8, "and II for the reasons given. The rolls 30, however, are effective to reduce the superabundant excess of saturant exteriorly carried by the web to an amount between 5% and 30% of the amount of the saturant which is within and fills the felted structure of the web at the temperature of said saturant at the rolls 30. Such an amount for the purposes of the invention is that which will be effective to deliver the web to the coating bath 4! completely filled with the saturant at its temperature upon reaching the bath 43. The invention does not rest broadly 0n the amounts of saturant carried by the web as indicated by the percentages above given. With different saturants both in kind and-physical qualities, other amounts may be used while carrying out the features of theinvention as to control and limitation of the superabundantexcess to secure the proper condition for absorption of the saturant while the web is cooling'and the final completion of full impregnation Just prior to the application of the sealing coating.

Having thus described my invention, I now claim:

1. Apparatus for impregnating an elongated web of felted fibrous structure which comprises means for moving the web in the direction of its length, means for substantially completely filling the structure of said web with impregnating ma-- terial at an elevated temperature and providing upon the faces of the web as it travels layers of impregnating material in addition to that initially carried by the hot impregnated web, means for I applying sealing coatings to the faces of said web, means for causing said web to travel through a cooling zone from said means for impregnating the web towards said means for applying said sealing coatings, means located adjacent the entrance of said cooling zone constructed and arranged to limit said impregnating material in said layers to an amount in excess of that which applying said sealing coatings.

assaom lugs to the faces of said web, means forcausin said impregnated web carrying said layers to applying said sealing coatings, and means actin upon said-cooling web for controlling the amount of impregnating material absorbed by said felted structure of the web in its travel through said cooling zone substantially to provide that which will Just completely fill the felted structure at the temperature of the impregnating material car-' ried by said web when it reaches said means to I 3. Apparatus according to claim 2 in which said means for controlling the amount of said impregnating material absorbed by the felted structure a of said web in said cooling zone includes means for varying the length of time of travel through at the temperature thereof upon reaching the coating means can substantially completely fill the felted structure without excess of said impreg- T nating material remaining on the faces of the web,

and means located in said cooling zone adjacent the faces of said web in its travel therethrough constructed and arranged to reduce the amount of said impregnating material to that which at the temperature thereof upon reaching said coating means can substantially completely fill the felted structure without excess of said impregnating material remaining on the faces of the web.

2. Apparatus for impregnating an elongated web of felted fibrous structure which comprises means for moving said web in the direction of its .length, means for substantially completely filling the felted structure of said web with impregnating material at an elevated temperature and providing upon one face of the web as it travels layers of impregnating material in addition to that carried within the felted structure of the hot impregnated web, means for applying sealing coattravel of said web through said cooling zone.

6. Apparatus for impregnating an elongated web of absorbent felted structure which comprises means for moving the web in the direction of its length, means for impregnating said web with impregnating material at an elevated temperature and for forming a layer thereof on a face of said moving web in amount in excess of that which will Just be absorbed by said web upon cooling thereof and said layer to a given temperature, means providing a cooling zone located' in the travel of theweb from said impregnating means for cooling the web and said layer to said given temperature, and means located in said cooling zone along the web from the point of entrance of said web into said zone a distance to provide substantial cooling of the web and said layer and arranged to remove a portion of said excess of said impregnating material in said layer but to leave an amount therein which will just be absorbed by said web upon cooling thereof and said impregnating material to said given temperature.

7. Apparatus for impregnating 'an elongated web of absorbent felted structure which comprises terial at an elevated temperature in amount in excess of that which will be absorbed by the felted structure of the web in cooling of said'web and said layers to a given temperature, means providing a cooling zone located in the travel of the web from said means for applying said layers to cool the web and said layers to said given temperature, andmeans located in said cooling zone along the web from the point of entrance of said web into said zone a distance to provide substantial cooling of the web and said layers and arranged to remove a portion of said excess of said impre nating material in said layers but to leave an amount therein which will just be absorbed by said web upon cooling thereof and said impregnating material to said given temperature.

LEONARD E. HAHN. 

